CN101429009A - Low-dielectric constant high-quality microwave ceramic medium and production process thereof - Google Patents

Abstract

The invention discloses a microwave dielectric ceramic with low dielectric constant and high quality and a method for preparing the same. The chemical composition constitution formula of the microwave dielectric ceramic with low dielectric constant and high quality is Mg2(Si, Al )O4, which consists of MgO, SiO2 and Al2O3, wherein the mol percentage of the MgO to the SiO2 to the Al2O3 is equal to 60-70 to 15-35 to 0-15. The microwave dielectric ceramic with low dielectric constant and high quality is used as a core material for electronic circuit substrates, syntonizers, filters, microwave substrates and microstrip lines, and has important application prospect and economic benefit on electronic circuit, microwave communication, satellite communication and radar system.

Description

A kind of low-dielectric constant high-quality microwave ceramic medium and preparation method thereof

Technical field

The invention belongs to electronic information material and devices field, be specifically related to a kind of novel low-dielectric constant high-quality microwave ceramic medium and preparation method thereof.

Background technology

Along with the fast development of micro-wave communication and Radar Technology, the research of microwave dielectric material is also towards the high extreme direction development of microwave.The exploitation specific inductivity less than 10, microwave dielectric resonator, wave filter and the microwave base plate material of the high Q value of low-loss and near-zero resonance frequency temperature coefficient become the key issue that electronic information technology develops.At present, be perovskite structure and 70～00 tungsten bronze structure microwave dielectric materials with calcium mainly with the specific inductivity of the microwave dielectric material sold on the market in 16～25 magnesium titanates system, 30～50 medium dielectric constant microwave medium barium system.Being lower than 10 microwave dielectric material for specific inductivity, having response speed and high-quality signal-selectivity fast in micro-wave communication, mainly is Al at present ₂O ₃, its specific inductivity is about 9-1, and microwave property is 150, and 000GHz～300 between the 000GHz, obtain fine and close Al ₂O ₃Pottery needs very high sintering temperature and special sintering mode.Developing a kind of novel low temperature sintering specific inductivity becomes the key of ICT development near the microwave-medium ceramics resonator material of silicon-dioxide.Present Mg ₂SiO ₄Use mainly as high-quality dielectric resonator, key issue is SiO in the ceramic building-up process ₂React generation perovskite structure MgSiO easily with MgO ₃The pyroxene phase, MgSiO ₃Specific inductivity 6～7, but loss is very big 10 ^-3About; Adjustment sintering process by routine with improve heat treating method and also be difficult to eliminate pyroxene existence mutually, the existence of pyroxene phase has worsened Mg ₂SiO ₄Microwave property, eliminate the second phase MgSiO like this ₃The existence of pyroxene phase just becomes very necessary.

Summary of the invention

The objective of the invention is to provides a kind of low-dielectric constant high-quality microwave ceramic medium and preparation method thereof at the deficiencies in the prior art.

In order to achieve the above object, the technical solution used in the present invention is as follows:

A kind of low-dielectric constant high-quality microwave ceramic medium, its chemical ingredients composition formula is:

Mg ₂(Si, Al) O ₄, it is by MgO, SiO ₂And Al ₂O ₃Form, wherein, MgO, SiO ₂And Al ₂O ₃Molar percentage be: MgO:SiO ₂: Al ₂O ₃=60～70:15～35:0～15.

The preparation method of above-mentioned low-dielectric constant high-quality microwave ceramic medium is characterized in that, may further comprise the steps:

(1) raw material is chosen: choose purity greater than 99.5% MgO powder, SiO ₂Powder and Al ₂O ₃Powder;

(2) batching: according to molar percentage MgO:SiO ₂: Al ₂O ₃=60～70:15～35:0～15 weighings mix, and 60 ℃～150 ℃ oven dry of baking oven are inserted in wet grinding after 12～24 hours;

(3) granulation: calcined 2-4 hour for 1000 ℃～1300 ℃ in corundum crucible, ball milling got synthetic material in 12～24 hours then, and adding mass percent after the synthetic material oven dry is sieved is the PVA of synthetic material 4～10%, gets the granulation material;

(4) moulding: the granulation material is inserted grinding tool at 98～100MPa forming under the pressure;

(5) sintering:, be cooled to the speed temperature control of 2 ℃～8 ℃ of per minutes then and be lower than furnace cooling behind 300 ℃～500 ℃ of the sintering temperature points at 1200 ℃～1500 ℃ sintering temperatures.

The invention has the beneficial effects as follows: the present invention adopts Al ₂O ₃Displacement Mg ₂SiO ₄SiO in the stoichiometry ₂, by sintering solid state reaction Al ₂O ₃Enter that framework becomes the Al-Si-O network structure in the tetrahedral skeleton structure of Si-O, form single phase Mg ₂(Si, Al) O ₄Solid solution ceramic, eliminate the existence of the second phase pyroxene phase, the ceramic dielectric constant is between 6～10, quality factor is 160, more than the 000GHz, as the manufactured materials of electronic circuit and microwave base plate, resonator, wave filter and microstrip line have good signal response speed and signal-selectivity, high temperature resistant, resistance to chemical attack, moisture resistance is wet and the favorable mechanical supporting capacity.

Embodiment

The present invention passes through Al in prescription ₂O ₃Displacement SiO ₂, Al ₂O ₃In sintering process, enter Si-O cyclic silicate island structure, form the Mg of single phase ₂(Si, Al) O ₄Solid solution ceramic is eliminated pyroxene second phase, improves the pottery prime factor, makes Mg ₂SiO ₄Microwave property reaches 160, more than the 000GHz.Simultaneously, specific inductivity is controlled between 6～10, and sintering temperature is controlled between 1200 ℃～1500 ℃, with present use Al on electron device ₂O ₃, MgTiO ₃, barium system or calcium is that perovskite ceramics is compared satisfying under the prerequisite that high-quality-factor uses, and has lower advantage of burning till temperature and specific inductivity.

Low-dielectric constant high-quality microwave ceramic medium of the present invention, its chemical ingredients composition formula is: Mg ₂(Si, Al) O ₄, can also be expressed as: MgOSiO ₂Al ₂O ₃It is by MgO, SiO ₂And Al ₂O ₃Form, wherein, MgO, SiO ₂And Al ₂O ₃Molar percentage be: MgO:SiO ₂: Al ₂O ₃=60～70:15～35:0～15.

Low-dielectric constant high-quality microwave ceramic medium of the present invention, concrete preparation process is as follows:

(1) raw material is chosen: MgO powder, purity 〉=99.5%; SiO ₂Powder, purity 〉=99.5%, Al ₂O ₃Powder, purity 〉=99.5%.

(2) batching: according to molar percentage MgO:SiO ₂: Al ₂O ₃=60～70:15～35:0～15 weighings mix, and 12～24 hours disposed slurries of wet grinding are inserted 60 ℃～150 ℃ oven dry of baking oven.

(3) granulation: in corundum crucible, calcined 2-4 hour for 1000 ℃～1300 ℃, ball milling got synthetic material in 12～24 hours once more, adding mass percent after the synthetic material oven dry is sieved is the PVA (polyvinyl alcohol polymer, polyvinyl alcohol) of synthetic material 4～10%, gets the granulation material.

(4) moulding: the granulation material is inserted grinding tool at 98～100MPa forming under the pressure.

(5) sintering:, be cooled to the speed temperature control of 2 ℃～8 ℃ of per minutes then and be lower than furnace cooling behind 300 ℃～500 ℃ of the sintering temperature points at 1200 ℃～1500 ℃ sintering temperatures.

At room temperature take out product, obtain low-dielectric constant high-quality microwave ceramic medium of the present invention.Product becomes size diameter 8～1mm, high 5mm cylinder through the grinding and polishing post-treatment, adopt the closed dielectric Resonant-cavity Method to carry out the microwave property test: the present invention enters by regulation and control Al that framework becomes the Al-Si-O network structure in the tetrahedral network skeleton structure of Si-O, forms Mg ₂(Si, Al) O ₄Sosoloid obtains single phase ceramics.The ceramic dielectric constant is 6～10, has fast signal response velocity of propagation, uses with the suitable unicircuit of low specific inductivity; Ceramic dielectric loss simultaneously is low less than 10 ^-5, Qf is 160,000～200, and 000GHz has high quality factor, and using in relay system, satellite communications and radar system is a kind of have very big application prospect microwave-medium substrate, microstrip line and resonator applications material.

Below in conjunction with a little examples the present invention and preparation method are further described.

Embodiment 1:

Take by weighing 80.6gMgO according to the present invention by stoichiometric, 60.1gSiO ₂Pour in the poly-tetrafluoro jar, add alcohol to jar high 2/3 a place sealing jar, put into planetary ball mill and grind 12h, the oven dry after 1000 ℃ the calcining 3 hours, grind again to dry behind the 12h and sieve, after adding the 5Wt%PVA granulation, be pressed into diameter 12mm height, the cylinder of 7mm is cooled to 1050 ℃ with 5 ℃ of temperature controls of per minute and cools to room temperature with the furnace behind 1350 ℃ of sintering 3h, takes out the paramount 5mm cylinder of ceramic both ends of the surface grinding and polishing, put into and close the cavate resonator cavity and test microwave property, get specific inductivity 7.0, Qf value 80,000GHz.

Embodiment 2:

Take by weighing 80.6gMgO according to the present invention, 57.1gSiO ₂, 2.6gAl ₂O ₃Pour in the poly-tetrafluoro jar, add alcohol to jar high 2/3 a place sealing jar, put into planetary ball mill and grind 24h, dry 1200 ℃ of calcining 3h, grind again to dry behind the 24h and sieve, after adding the 5Wt%PVA granulation, be pressed into diameter 12mm, the cylinder of high 7mm is cooled to 1150 ℃ with 5 ℃ of temperature controls of per minute and cools to room temperature with the furnace behind 1400 ℃ of sintering 3h, takes out ceramic both ends of the surface through the paramount 5mm cylinder of grinding and polishing, put into and close the cavate resonator cavity and test microwave property, get specific inductivity 7.1, Qf value 180,000GHz.

Embodiment 3:

Take by weighing 80.6gMgO according to the present invention, 54.1gSiO ₂, 5.1gAl ₂O ₃Pour in the poly-tetrafluoro jar, add alcohol, put into planetary ball mill and grind 24h to jar high 2/3 a place sealing jar, dry 1200 ℃ of calcining 3h, grind again dry behind the 24h and sieve, after the adding 5Wt%PVA granulation, be pressed into diameter 12mm, the cylinder of high 7mm is cooled to 1100 ℃ with 5 ℃ of temperature controls of per minute and cools to room temperature with the furnace behind 1400 ℃ of sintering 3h, takes out the paramount 5mm of ceramic both ends of the surface grinding and polishing, put into and close the cavate resonator cavity and test microwave property, get specific inductivity 7.8, Qf value 200,000GHz.

Above-mentioned embodiment is used for explaining the present invention, rather than limits the invention, and in the protection domain of spirit of the present invention and claim, any modification and change to the present invention makes all fall into protection scope of the present invention.

Claims (2)

1. a low-dielectric constant high-quality microwave ceramic medium is characterized in that, its chemical ingredients composition formula is: Mg ₂(Si, Al) O ₄, it is by MgO, SiO ₂And Al ₂O ₃Form, wherein, MgO, SiO ₂And Al ₂O ₃Molar percentage be: MgO:SiO ₂: Al ₂O ₃=60～70:15～35:0～15.

2. the preparation method of the described low-dielectric constant high-quality microwave ceramic medium of claim 1 is characterized in that, may further comprise the steps:

(1) raw material is chosen: choose purity greater than 99.5% MgO powder, SiO ₂Powder and Al ₂O ₃Powder.

(2) batching: according to molar percentage MgO:SiO ₂: Al ₂O ₃=60～70:15～35:0～15 weighings mix, and 60 ℃～150 ℃ oven dry of baking oven are inserted in wet grinding after 12～24 hours.

(3) granulation: calcined 2-4 hour for 1000 ℃～1300 ℃ in corundum crucible, ball milling got synthetic material in 12～24 hours then, and adding mass percent after the synthetic material oven dry is sieved is the PVA of synthetic material 4～10%, gets the granulation material.

(4) moulding: the granulation material is inserted grinding tool at 98～100MPa forming under the pressure.

(5) sintering:, be cooled to the speed temperature control of 2 ℃～8 ℃ of per minutes then and be lower than furnace cooling behind 300 ℃～500 ℃ of the sintering temperature points at 1200 ℃～1500 ℃ sintering temperatures.